Well screen



Nov. 21, 1961 3,009,519

J- D. BROWN WELL SCREEN Filed July 51, 1959 4/0/7795 .5. Brown INVENTOR.

A TTOIP/VF v F United States Patent 3,009,519 Patented Nov. 21, 1961 The present invention relates to a well screen.

In obtaining water from water Wells, it is desirable to exclude fine sand particles which may be present in or about the producing formation from the well string which is inserted in the well bore and through which the desired liquids or fluids flow to the earths surface. In order to exclude the sand particles from the string of well pipe through which the liquids are conducted to the earths surface, various types of devices commonly called screens have been heretofore employed.

The well screens as presently employed may be formed. by wrapping wire on the outer periphery of a perforated pipe, each wrap of wire being spaced apart a predetermined distance to inhibit the flow of sand particles therethrough and into the perforated pipe, but accommodating the flow of well liquids and fluids therethrough. This type of well screen is extremely costly to manufacture. Other types of well screens use a plurality of rings which are stacked on the perforated pipe, the rings having projections thereon to space them apart to accommodate the flow of well fluid and liquid therethrough, while inhibiting the flow of sand therebetween.

Certain problems have arisen in the use of well screens employing the above constructions. One disadvantage is that no suitable means are provided for inhibiting damage to the well screen as it is being lowered into the well bore. It can be appreciated that the producing formation from which the well liquids and fluids are to be received may be several hundred, or several thousand feet below the earthssurface, and of course, the well screen must be positioned in the proximity of the producing formation so that the fluids may flow therefrom and into the string to which ---Lhe well screen is attached and thence to the earths surface. Quite frequently, as well screens of prior constructions are lowered in to the well bore, they drag against the surface of the well bore, or hit thereagainst as they are being lowered so that the well screen is damaged and by the time it reaches its destination may be for all intents and purposes ineffective in operation.

Another disadvantage with well screen constructions heretofore used is that the well screen is not spaced radially relative to the perforated pipe section on which it is positioned. Therefore, when the space between the adjacent wraps of wire, or between the adjacent stacked rings, becomes clogged with sand or other foreign matter from the producing formation, there is no way for the well liquids to gain access through the next adjacent space into the perforations.

Additionally, a great deal of difliculty has been encountered with well screen constructions of prior art in that their exterior surface is constructed and arranged so that the sands from the formations pack closely around the well screen and close it oh, so as to eliminate or greatly reduce the flow of well fluids through the screen.

Another disadvantage of well screen constructions of the prior art is that a great deal of difficulty is encountcred in corrosion of the well screen, and in electrolysis. Also, the flow of water through the well screen forms encrustations on the well screen so that after a period of time the well screen becomes clogged to such an extent that it must be replaced.

The present invention is adapted to overcome all of the above and other objections presently encountered in well screen constructions.

One of the objects of the present invention is to provide a well screen construction wherein the well screen is formed by a plurality of stacked rings, the stacked rings having projections to space [them apart longitudinal- 1y for the flow of water or other liquids therethrough and into the perforated pipe section on which they are positioned, and the stacked tings also employing ribs to space them radially relative to the perforated pipe section where- 'by access may be gained through any one of the longitudinal spaces between adjacent rings to any of the perforations in the well pipe.

Another object of the present invention is to provide a well screen formed of stacked rings which have projec tions to space them radially, and projections to space them longitudinally on a perforated pipe section, the rings also having an exterior surface of suitable contiguration so that when they are positioned on the perforated pipe section, an irregular surface is provided on the well screen to inhibit packing of sand and foreign matter therearound so as to close off flow through the well screen.

Yet a further object of the present invention is to provide a well screen formed of a plurality of stacked rings wherein the rings are provided with projections to space them relative to each other to permit the flow of oil therethrough while inhibiting the flow of sand or other foreign material from the producing formation, and the rings also having projections to space them radially relative to a perforate type section on which they may be positioned, and an outer construction or surface configuration to inhibit the packing of sand or other foreign matter against the well screen, the well screen also including annular projections adjacent each of its ends, and at intermediate points throughout its length, which projections are of greater diameter than the diameter of the well screen to protect the well screen from damage as it is lowered into the well bore.

Another object of the present invention is to provide a well screen which employs a plurality of annular ring members positioned at intervals throughout its length, which ring members are of substantially greater diameter than the diameter of the well screen, to inhibit damage to the well screen as it is being lowered into the well bore.

Still another object of the present invention is to provide a well screen formed of plastic rings of a peculiar configuration to inhibit packing of the formation around the plastic rings, the plastic rings also eliminating, or greatly reducing electrolysis, corrosion and encrustation.

Other objects and advantages of the present invention will become more readily apparent from a consideration of the following description and drawings wherein:

FIG. 1 is a broken side elevation illustrating the components of the well screen, including a perforate pipe section with the rings of the present invention positioned on a portion thereof, and also illustrating the arrangement of the annular members or projections adjacent each end of the well screen, and at intervals throughout its length, which inhibit damage to the well screen as it is being lowered into position in the well bore;

FIG. 2 is a sectional view on the line 2-2 of FIG. 1 and illustrates in greater detail the structural arrangement of the rings including the projections which space the rings longitudinally relative to each other for the flow of oil therethrough and into the perforate pipe section on which the rings are positioned, and the ribs or pro jections for spacing the rings radially relative to the perforate pipe section on which they are positioned; and

FIG. 3 is an enlarged partial sectional view of the rings to better illustrate their structural arrangement and to show in greater detail the configuration of the outer surface of the rings to aid in inhibiting packing of the earth formation therearound.

Attention is directed first of all to FIG. 1 wherein the invention is illustrated generally by the reference numeral 2. As previously noted, a well pipe, generally called the producing string, is illustrated at 3 and extends from the earths surface into the Well bore whereby well fluids from the earth may be conducted through the well screen and upwardly therethrough and to the earths surface. The lower portion of the pipe 3 is generally perforated as illustrated at 4 and is adapted to be positioned in the general area, or adjacent the producing formation from which the well fluids are to be received. The lower end 5 of the pipe 3 below the foraminated portion 4 is closed off by any suitable means not shown, so that any fluid from the earths formation must be received through the well screen generally designated at 3' and into the pipe 3 and thence may flow to the earths surface.

It will be noted that the well screen designated generally at 3' includes the annular flange members or annular projections 6 and 7 which are positioned adjacent each end of the foraminated or perforated pipe section 4 as illustrated in FIG. 1, the flanges 6 and 7 serving to position and retain the other components of the well screen 3 in position on the perforate portion 4 therebetween.

In some circumstances the well pipe 3 and the well screen 3' will be formed of plastic material. When this is the case, the bottom annular flange member 7 may be secured in position on the lower end 5 of the well pipe 3 by any suitable means such as a plastic glue or the like. Thereafter the rings illustrated at 10 may be stacked in position on the shoulder 11 of the lower flange 7 until all of the area of the perforate portion 4 in the well pipe 3 has been covered. Thereafter the annular flange 6 may be moved into position on the pipe 3 so as to abut the uppermost ring (not shown) and may be secured in position by any suitable means such as a plastic glue or the like to hold the ring members 10 between the annular flanges 6 and 7.

If the well pipe 3 is formed of metal, then the annular flange 7 may be secured into position by any suitable means such as welding or the like, and similarly the flange member 6 may be secured in position by any suitable means such as welding or the like.

It will be noted that the diameter of the annular end flanges 6 and 7 is substantially greater than the outer diam eter of the well screen 3. Also, it will be further noted that a ring member as illustrated at 12 is positioned around the perforated section and is also of substantially greater diameter than the outer diameter of the rings 10 forming the well screen 3'. Any suitable number of annular members 12 may be spaced at intervals between the annular end flanges 6 and 7, and in practice, it has been found that the annular ring members 12 may be positioned at intervals of one foot along the perforated pipe portion 4; however, the distance between the annular members 12 may be varied as desired.

The size of the annular end members 6 and 7 and the size of the annular members 12 being substantially greater than the size of the rings 10, inhibits damage to the rings 10 of well screen 3' as the screen 3' is lowered into position in the well bore in the earths surface. As a matter of fact, the rings 12, and the annular end flanges 6 and 7 serve as bumpers or guides so as to prevent the rings 10 of the well screen 3 from engaging the well bore wall and becoming damaged as the well screen is lowered on the well pipe 3 into the well bore to its final position.

The rings 12 may form a sliding fit on the outer periphery of the pipe 3 and will fit snugly thereabout, and will not be spaced radially from the perforation 4 in the pipe 3 as are the rings 10.

In FIG. 2 the details of construction of the rings 10 are better illustrated and it will be noted that the bottom surface 13 of each ring is provided with a plurality of circumferentially spaced projections 14, which projections are of a suitable length to space the rings apart a predetermined distance as illustrated or represented by the reference numeral 15' in the drawings. The distance 15 between the rings will be varied depending upon the size sand particles in the producing formation in which the well screen 3' is to be used. The projections 14 may be integrally formed on the ring 10 and as best seen in FIG. 3 it will be noted that the bottom surface 13 is tapered inwardly and upwardly so that the space as represented by the reference numeral 17 between the inner edges of the rings is greater than the vertical space 15 at the outer annular edge of the ring. It will be noted that the bottom 18 of the projection 14 is substantially horizontal so that they may be stacked on the horizontal top surface 19 of an adjacent ring. From the foregoing, it can be appreciated that any suitable spacing may be provided between the rings as desired, depending upon the size of particles to be excluded from the well screen, and from the interior of the well pipe 3.

It has been discovered that a great deal of difficulty is encountered in well screens presently employed in that in some instances the space 15 becomes clogged with sand, and if the rings 10 are seated immediately on the outer periphery 20 of the well pipe 3, some of the perforations 4 may thereby be blocked off.

To overcome this difliculty, a plurality of longitudinal ribs or projections 21 are provided on the inner surface 22 of the ring 10, and are circumferentially spaced thereabout so as to radially space the ring 10 relative to the outer surface 20 as illustrated by the numeral 23 in FIG. 2. Thus, if the space or spaces between any two rings or group of rings become blocked off by sand, access may still be had to the perforations over which they are positioned by flow through the immediately adjacent group or series of rings which is not stopped up.

Another problem encountered in well string constructions is that it has been determined that the sand or other foreign material from producing formations tends to pack or conglomerate around the well screen 3'. Heretofore, well screen constructions have been substantially smooth or regular on their outer periphery so that when the well sand moved thereagainst, it tends to pack against the well screen.

In order to overcome this problem it will be noted that the well screen 3' is provided with a substantially irregular outer configuration or outer surface as represented generally by the numeral 27. The irregular configuration or outer surface 27 is defined or formed by means of the annular outer surface 28 which is formed on each of the rings, which surface is downwardly and inwardly tapered as best illustrated in FIG. 3 so that the upper edge 29 of each ring projects outwardly around its circumference in relation to the lowermost edge 30 of an adjacent ring. Also, it will be noted that the end annular flanges 6 and 7 as well as the spaced annular members 12 are also provided with irregular surfaces as illustrated at 32 and 33 and 34 respectively to further provide an exterior surface 27 on the well screen 3' which is irregular. This irregular surface on the well screen 3' aids in inhibiting packing of sand or other foreign material from the producing formation around the well screen thereby greatly increasing the useful life of the well screen prior to cleaning thereof.

While it is believed that the construction and manner of building the well screen of the present invention is apparent by reason of the foregoing, to further amplify and describe, it will be assumed that the present invention is to be used on metal pipe. The rings 10 may be formed either of metal or plastic, and it has been determined that any suitable plastic which will withstand the temperatures and pressures in the well in which it is to be positioned, and which will not react with the liquid or fluid substances which pass through the well screen 3' may be employed. The plastic termed Marlex has been found quite satisfactory for this purpose. In forming the well screen 3, the annular flange 7 may be first positioned on the well pipe 3, and this annular flange 7 may be formed of metal. If the pipe 3- is of metal, the flanges 6 and 7 may be secured thereto by any suitable means such as welding. Thereafter the rings 10 are stepwise positioned about the pipe so that the projections on one ring rest on the top surface of an adjacent ring as better illustrated in FIGS. 1 and 3. At suitable intervals the members 12 are slipped into position on the perforated portion of the well pipe, and the members 12 are provided with an annular shoulder 12' at each end which abuts the adjacent ring. The well screen may be any suitable length, and it is not uncommon for the well screen to be as much as forty feet long; however, the most popular or the average size well screen is generally six to ten feet long.

After the rings 10* have been positioned on the perforated pipe section 4, then the annular flange member 6 may be secured in position by any suitable means such as welding or the like and the well screen is then ready to be secured to a pipe section so that it can be lowered into the well bore by connecting additional pipe sections thereto.

The preferred form of the invention is wherein the rings 10 are formed of plastic. As previously noted, any suitable plastic may be used, and particularly any plastic which will not deteriorate in the presence of the liquid which flows therethrough. One of the major problems with well screen constructions for use in water wells of the prior art is that encrustations form on the well screen which clog the well screen and necessitate removal thereof, or washing operations to try to remove the encrustations from the well screen. The encrustations are formed by chemical substances in the liquid passing through the well screen and in well screen constructions of the prior art, these chemical substances adhere to the well screen and build up thereon over a period of time, so as to close off the openings in the screen.

In addition to the encrustations, it can be appreciated that where the Well screen is formed of a metal dissimilar to the pipe on which it is suspended, or associated with, electrolysis occurs, thereby causing damage either to the pipe or to the well screen. Also, the well screen when formed of metal corrodes over a period of time, even when anti-corrosive materials such as stainless steel are employed.

It can be appreciated that the rings 10, being formed of plastic, eliminate the problem of corrosion, since such plastic material is non-reactive to water or to other liquids which may flow through the well screen. Also, since the plastic material is substantially non-conductive, the problem of electrolysis is eliminated, and it has been discovered that the well screen, when formed of plastic, greatly reduces, if not completely eliminates the problem of encrustation which occurs with well screen constructions of other types.

The present invention is peculiarly adapted for use with water wells, and they have use in other situations where the well pressure and temperature and the constituents involved will not affect the plastic rings 10.

The annular end flanges 6 and 7 as well as the annular members 12 inhibit damage to the rings 10 in that such members act as bumpers or guides to prevent the rings 10 from contacting the well bore wall as it is lowered downwardly into the well bore. When the well screen is positioned at the desired location in the well bore, it has been determined that the irregular surface configuration 27 thereon inhibits the packing of sand or other foreign material from the producing formation around the well screen, thereby greatly increasing the period of its use before requiring the screen to be cleaned or otherwise treated.

Broadly the invention relates to a well screen and more particularly to a well screen which is constructed and arranged to greatly increase the useful life thereof before requiring cleaning or other treatment.

What is claimed is:

1. A well screen comprising a foraminated tubular core, spaced flange means secured to said core, a plurality or rings stacked between said flange means, each of said rings having a top surface, an inner surface, an annular outer surface, and a bottom surface, ribs circumferentially spaced on said inner surface of said rings to abut said core and space said rings outwardly therefrom, projections engaging and spacing said rings so that said top surface and bottom surface of adjacent rings are spaced vertically to form flow passages, said top and bottom surfaces diverging inwardly whereby the vertical spacing of adjacent rings increases from the outermost edges of said rings toward the innermost edges of said rings to inhibit clogging of the How passages formed by said surfaces, and said outer annular surface on said rings being inwardly and downwardly tapered to thereby project the upper edge of each of said rings outwardly around its circumference in relation to the edge of said bottom surface on the ring immediately thereabove.

2. A well screen comprising a foraminated tubular core, spaced flange means secured to said core, a plurality of rings stacked between said flange means, each of said rings having a top surface, an inner surface, an annular outer surface, and a bottom surface, ribs circumferentially spaced on said inner surface of said rings to abut said core and space said rings outwardly therefrom, projections engaging and spacing said rings so that said top surface and bottom surface of adjacent rings are spaced vertically to form flow passages, said top and bottom surfaces diverging inwardly whereby the vertical spacing of adjacent rings increases from the outermost edges of said rings toward the innermost edges of said rings to inhibit clogging of the flow passages formed by said surfaces, said outer annular surface on said rings being inwardly and downwardly tapered to thereby project the upper edge of each of said rings outwardly around its circumference in relation to the edge of said bottom surface on the ring immediately thereabove, and annular members positioned at intervals on said core, said annular members having an outer diameter greater than the outer diameter of said rings to protect said rings as the well screen is set in a well bore.

References Cited in the file of this patent UNITED STATES PATENTS 146,902 Hawley Jan. 27, 1874 1,001,523 Hiester Aug. 22, 1911 1,654,601 Records et a1 Jan. 3, 1928 2,004,071 Hannesschlager June 4, 1935 2,933,137 DAudiflret et al Apr. 19, 1960 

